The Seattle company's profit more than doubled to $1.9 billion during the all-important holiday quarter, extending its streak of profitability over two and a half years. The company has long plowed most of the money it makes to build products, roll out services and construct warehouses, but it is no longer racking up a string of losses.

Its profit was helped by a tax benefit of $789 million as part of the new tax overhaul, Amazon said.